In a projector, light emitted from an illumination optical system is modulated with use of a modulation optical system such as a digital micromirror device (DMD) or a liquid crystal panel, and the modulated light is enlarged and projected onto a screen provided outside the device with use of a projection lens. The projection lens may have a configuration of being removable from the projector including the illumination optical system and the modulation optical system. Through replacement of the projection lens, the projector is adaptable to a wide variety of projection distances which differ depending on use.
As a mechanism configured to mount the projection lens to the projector, there have been known mechanisms of, for example, a bayonet type and a spigot type. In any of those types, a flange portion provided on the lens unit side is pressed against a lens mount main body provided on the projector side so that the lens unit is retained in a certain posture with respect to the lens mount main body.
Moreover, in a lens mounting device disclosed in Patent Literature 1, an angle adjustment plate is provided to the lens mount main body, and the flange portion of the lens unit is brought into press contact with the angle adjustment plate. A plurality of angle adjustment screws are threadably engaged with the angle adjustment plate, and distal ends of the angle adjustment screws are held in abutment against the lens mount main body. Through changes in amount of thread engagement of each angle adjustment screw, the installation angle of the angle adjustment plate with respect to the lens mount main body can be changed. With this, the lens unit is retained on the projector in a posture with the angle adjustment plate as a reference, and an angle accuracy of an optical axis of the lens unit with respect to an optical axis of the projector can be suitably corrected.